Dynamic Switch Between Two Adhesion Phenotypes in Colorectal Cancer Cells.

The hematogenous metastatic cascade is mediated by the interaction of cancer cells and the endothelial cell lining of blood vessels. In this work, we examine the colon cancer cell line COLO 205, which grows simultaneously in both adherent and suspended states in culture and can serve as a good model for studying tumor heterogeneity. The two subpopulations of cells have different molecular characteristics despite being from the same parent cell line. We found that the ratio of adherent to suspended cells in culture is maintained at 7:3 (equilibrium ratio). The ratio was maintained even when we separate the two populations and culture them separately. After 8 h in culture the equilibrium was achieved only from either adherent or suspended population. The adherent cells were found to express less E-selectin binding glycans and demonstrated significantly weaker interaction with E-selectin under flow than the suspended cells. Manipulation of the epithelial-mesenchymal transition (EMT) markers β-catenin and E-cadherin expression, either by siRNA knockdown of β-catenin or incubation with E-cadherin antibody-coated microbeads, shifted the ratio of adherent to suspended cells to 9:1. Interestingly, human plasma supplemented media shifted the ratio of adherent to suspended cells in the opposite direction to 1:9, favoring the suspended state. The dynamic COLO 205 population switch presents unique differential phenotypes of their subpopulations and could serve as a good model for studying cell heterogeneity and the EMT process in vitro.